It has long been known that dye images fade especially in sunlight and despite work over the years to improve dye stability further improvement is required.
Various approaches have been attempted to improve dye stability in the finished photographic product. For example in U.S. Pat. No. 2,353,262 (Kodak) it is disclosed that the admixture of a coupler and a non-coupling compound of a similar structure reduces crystallization. Crystallization is believed to be one cause of lack of dye stability in the finished product.
Later in GB-A-1,285,254 (Konishiroku) there is disclosed the use in a photographic process of a photographic coupler along with a solvent of a similar structure. This arrangement improved crystallization characteristics, Dmax and contrast when compared to systems without the solvent.
U.S. Pat. No. 4,774,166 (Fuji) discloses the use of ballasted alcohols which are said to improve photographic activity.
Further EP-A-0,426,043 (Fuji) reveals high viscosity coupler solvents which can be solid in use, however none of the forgoing disclosures are directed specifically to the improvement of dye stability in the finished photographic product.
It would be desirable then, to provide photographic products which have good dye stability.